Sample HTTP Server Golang

main.go

package main

import (
	"encoding/json"
	"net/http"
)

type input struct {
	Word    string `json:"word"`
	Synonym string `json:"synonym"`
}

type output struct {
	Word     string   `json:"word"`
	Synonyms []string `json:"synonyms"`
}

func handler(w http.ResponseWriter, r *http.Request) {

	setCORS(w)

	switch r.Method {

	// OPTIONS ...
	case "OPTIONS":

	// GET localhost:8080/synonyms?word=begin
	case "GET":
		word := r.URL.Query().Get("word")

		// TODO search synonyms by the the "word" query parameter
		o, _ := json.Marshal(
			&output{
				Word:     word,
				Synonyms: []string{"a", "b", "c"},
			},
		)
		w.Write(o)

	// POST localhost:8080/synonyms
	case "POST":
		d := json.NewDecoder(r.Body)
		i := &input{}
		err := d.Decode(i)
		if err != nil {
			http.Error(w, err.Error(), http.StatusInternalServerError)
		}
		// TODO insert the input "i" into data structure
		// ...
	default:
		w.WriteHeader(http.StatusMethodNotAllowed)
	}
}

func setCORS(w http.ResponseWriter) {
	w.Header().Set("Access-Control-Allow-Origin", "*")
	w.Header().Set("Access-Control-Allow-Methods", "POST, GET, OPTIONS, PUT, DELETE")
	w.Header().Set("Access-Control-Allow-Headers", "Accept, Content-Type, Content-Length, Accept-Encoding, X-CSRF-Token, Authorization")
}

func main() {
	http.HandleFunc("/synonym", handler)
	http.ListenAndServe(":8080", nil)
}